Factors determining variation in colour morph frequencies in invasive Harmonia axyridis populations

The Harlequin ladybird Harmonia axyridis Pallas, native to eastern Asia, is an invasive, non-native species that has recently achieved an almost worldwide distribution. A conspicuous feature of this species is colour polymorphism of the elytra. In its native area, the populations consist of a recessive non-melanic morph, several dominant melanic morphs and small numbers of other (rare) morphs. The morph proportions in native populations have been intensively studied and vary with geographic area, climate and time. In contrast, colour polymorphism in invaded regions has been little studied. We examine and try to account for the morph frequencies observed across the different invaded regions. In America, monomorphic populations consist of the non-melanic morphs while European populations contain also melanic morphs. In particular geographic areas of Europe, the average percentage of the non-melanic morphs varied between 78 and 99%. It was highest in the lowlands of northern Italy and central and northern Europe and decreased in the Alps and western (Spain, UK) and eastern (southeast Russia) margins of the recently invaded area. In central Europe the frequency of the non-melanic morphs decreased over the course of the year but increased over the years from 2010 to 2018. The local differences might thus arise through gradual change of the morph composition of the founder invasive, non-native population. However, the variation in non-melanic morph frequency was not correlated with climatic characteristics that might affect coccinellid polymorphism. The observed rate of change in morph proportions in our data was too small to explain the diversification of what was supposedly a uniform invasive, non-native population at the point of introduction

The harlequin ladybird, Harmonia axyridis: global perspectives on invasion history and ecology

The harlequin ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), is native to Asia but has been intentionally introduced to many countries as a biological control agent of pest insects. In numerous countries, however, it has been introduced unintentionally. The dramatic spread of H. axyridis within many countries has been met with considerable trepidation. It is a generalist top predator, able to thrive in many habitats and across wide climatic conditions. It poses a threat to biodiversity, particularly aphidophagous insects, through competition and predation, and in many countries adverse effects have been reported on other species, particularly coccinellids. However, the patterns are not consistent around the world and seem to be affected by many factors including landscape and climate. Research on H. axyridis has provided detailed insights into invasion biology from broad patterns and processes to approaches in surveillance and monitoring. An impressive number of studies on this alien species have provided mechanistic evidence alongside models explaining large-scale patterns and processes. The involvement of citizens in monitoring this species in a number of countries around the world is inspiring and has provided data on scales that would be otherwise unachievable. Harmonia axyridis has successfully been used as a model invasive alien species and has been the inspiration for global collaborations at various scales. There is considerable scope to expand the research and associated collaborations, particularly to increase the breadth of parallel studies conducted in the native and invaded regions. Indeed a qualitative comparison of biological traits across the native and invaded range suggests that there are differences which ultimately could influence the population dynamics of this invader. Here we provide an overview of the invasion history and ecology of H. axyridis globally with consideration of future research perspectives. We reflect broadly on the contributions of such research to our understanding of invasion biology while also informing policy and people

A revision of the cladoceran genus Simocephalus (Crustacea, Daphniidae)

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Southern Range Expansion of the Emerald Ash Borer, Agrilus planipennis, in Russia Threatens Ash and Olive Trees in the Middle East and Southern Europe

Agrilus planipennis (Coleoptera: Buprestidae) is the most serious invasive pest of ash trees (Fraxinus spp., Oleaceae) in the world. It has not yet reached the range of olive tree plantations, however it has been shown to complete its life cycle in this host tree. This pest native to East Asia was first found in Europe in Moscow in 2003 and has been spreading ever since. The aims of this study were to determine if the southern border of the range has already reached the Caucasus and to assess the potential range in this region based on host availability and heat availability. In 2021, we surveyed ash trees south to the known range in Russia. We did not find the pest in six cities in the North Caucasus region but found it in the city of Azov close to the Caucasus. Analysis of information about 550 localities of ash trees in the Caucasus showed that Fraxinus spp. is common throughout the region. The calculation of annual growing degree days base 10 °C indicated that the places where Fraxinus spp. grow above 1500 m are too cold for A. planipennis and therefore could potentially become a refuge for ash trees. The spread of A. planipennis to the Caucasus is of concern. First, the forest ecosystems of this region are endangered, since European ash Fraxinus excelsior is much more common there than in the currently infested regions in Russia. Second, the Russian Caucasus can become the gateway to Georgia, Armenia, Azerbaijan, Turkey and other countries of the Middle East and Southern Europe. We propose using Fraxinus angustifolia, F. ornus and Olea europaea growing in the Caucasus and adjacent regions as sentinel trees for the monitoring and pest risk assessment of these tree species

Low Heat Availability Could Limit the Potential Spread of the Emerald Ash Borer to Northern Europe (Prognosis Based on Growing Degree Days per Year)

Emerald ash borer Agrilus planipennis (Coleoptera: Buprestidae) is one of 20 priority quarantine pests of the European Union. It is native to Asia and is established in the USA, Canada, European Russia, and Ukraine. We made the first prognosis of the potential range of A. planipennis in Europe based on heat availability. Mean annual growing degree days base 10 °C (AGDD10) was calculated for each grid square (0.25° × 0.25° latitude x longitude degrees) on the Earth’s surface. Minimal AGDD10 recorded in the grid squares currently occupied by A. planipennis was 714° in Asia, 705° in North America, and 711° in European Russia. Agrilus planipennis has never been recorded in localities with AGDD10 below 700°. If the phenotypic plasticity would not allow this species to overcome this threshold, cold regions of Europe would probably not be invaded by A. planipennis. Thus, Fraxinus excelsior could potentially escape from A. planipennis in some regions of Norway, Sweden, Finland, Ireland, and Great Britain

Rigorous Morphological Studies Confirm That the Classical Object of Pest Control Chilocorus kuwanae Is the Same Species as Ch. renipustulatus (Coleoptera: Coccinellidae)

The ladybug Chilocorus kuwanae, which was described in Japan, has been used for biological control of pests for 100 years. Chilocorus kuwanae was recently synonymized with Ch. renipustulatus described in Europe. The synonymy was based on the examination of few specimens. Our aim is to verify this synonymy. We studied all characters previously used to distinguish these taxa: eight metric and nine qualitative characters. Examination of 107 specimens from Japan and Sakhalin and 174 specimens from Europe showed that the ranges of variability in all characters in Asian and European specimens strongly overlap. There are no characters with interspecific hiatuses. Analysis with Amadon’s criteria showed that Asian and European specimens also do not represent different subspecies. Conclusions: (1) No differences between the specimens from Asia (Japan and Sakhalin) and Europe were found at specific or subspecific levels. Chilocorus kuwanae is a junior synonym of Ch. renipustulatus. (2) The releases of “Chilocorus kuwanae” in Europe and the Caucasus did not represent classical biological control since the same species was native to these regions. (3) A thorough taxonomical revision with the study of morphological variability should be conducted before the introduction of any species to new regions. (4) Taxonomical conclusions based on morphological studies should be confirmed by statistical methods

Alien Coccinellidae (Ladybirds) in Sochi National Park and its vicinity, Russia

About 20 alien species of Coccinellidae were released for biological control of pests in the Caucasus. Some of them were reported to be established, but no monitoring of their populations was conducted. So the current state of the populations is unknown. In particular, it was unknown what alien ladybirds occur in Sochi National Park. Survey of Coccinellidae in Sochi National Park and the city of Sochi in 2013, 2016 and 2017 has revealed that the following alien ladybirds occur in the region: Harmonia axyridis, Cryptolaemus montrouzieri, Serangium montazerii and Lindorus lophantae. Harmonia axyridis is an Asian species, which has recently become a global invader. It is a top-predator which has caused a decline of ladybirds in many regions of the world. In 2012 the first established population of this species was found in the Caucasus, namely in Sochi. Now H. axyridis has spread along the whole Black Sea coast of the Caucasus and has become abundant in the region. It is abundant not only in the city of Sochi, but also in the mountain forests of Sochi National Park. It could potentially have a serious impact on native ecosystems, especially on ladybirds. Probably the current population of H. axyridis in the Caucasus has appeared as a result of spread from Western Europe and releases of specimens for biocontrol. Cryptolaemus montrouzieri and Lindorus lophantae introduced from Australia and Serangium montazerii introduced from India have been found only in the city of Sochi and are not abundant. Probably they do not affect the ecosystems of Sochi National Park now. But the monitoring of populations of these alien species is necessary, since established populations exist in the region

Low Heat Availability Could Limit the Potential Spread of the Emerald Ash Borer to Northern Europe (Prognosis Based on Growing Degree Days per Year)

Emerald ash borer Agrilus planipennis (Coleoptera: Buprestidae) is one of 20 priority quarantine pests of the European Union. It is native to Asia and is established in the USA, Canada, European Russia, and Ukraine. We made the first prognosis of the potential range of A. planipennis in Europe based on heat availability. Mean annual growing degree days base 10 °C (AGDD10) was calculated for each grid square (0.25° × 0.25° latitude x longitude degrees) on the Earth’s surface. Minimal AGDD10 recorded in the grid squares currently occupied by A. planipennis was 714° in Asia, 705° in North America, and 711° in European Russia. Agrilus planipennis has never been recorded in localities with AGDD10 below 700°. If the phenotypic plasticity would not allow this species to overcome this threshold, cold regions of Europe would probably not be invaded by A. planipennis. Thus, Fraxinus excelsior could potentially escape from A. planipennis in some regions of Norway, Sweden, Finland, Ireland, and Great Britain

Alien leaf beetles (Coleoptera, Chrysomelidae) of European Russia and some general tendencies of leaf beetle invasions.

Invasions of leaf beetles can cause tremendous economic consequences because some of these insects become major pests in invaded territories. We present the first inventory of alien Chrysomelidae of European Russia that appeared in the region in the 20th and 21st centuries (9 species) with analysis of the history of their invasions and detailed maps of distribution. This case study revealed some general tendencies of invasions of leaf beetles: (1) Recently, a dramatic increase in the rate of Chrysomelidae invasions is observed, which reflects the increase in international trade of living plants; (2) Alien leaf beetles can spread quickly, occupying almost all of Europe within several decades; (3) When the range of some leaf beetle species is quickly expanding, or when the species has been recorded established somewhere outside the native range, this species should be regarded as a potential invader worldwide. and (4) Alien leaf beetles usually occur on alien or cultivated plants, but some become naturalized in native communities. The specific information was the following. Two species native to the Mediterranean region, Chrysolina americana (feeds on Rosmarinus and Lavandula) and Leptomona erythrocephala (feeds on Lotus corniculatus) were recorded in European Russia for the first time. A polyphagous pest of floriculture Luperomorpha xanthodera native to China and Korea and a pest of soybeans Medythia nigrobilineata native to east Asia have been in the region since 2016. A pest of tobacco Epitrix hirtipennis native to North America has occurred since 2011. A pest of corn Diabrotica virgifera was intercepted at the border of Russia in 2011 but has not established. Three alien species have been in the region since the 20th century: Zygogramma suturalis introduced from North America for control of Ambrosia, Phyllotreta reitteri native to Afghanistan and Tajikistan and feeding on Lepidium latifolium, and the Colorado potato beetle Leptinotarsa decemlineata

Alien Pests Can Spread Quickly: Wooly Ash Aphid Prociphilus fraxinifolii (Hemiptera: Eriosomatidae) Has Occupied Europe in 18 Years

Prociphilus fraxinifolii (woolly ash aphid) is a pest of ash trees (Fraxinus spp.). This species, which is native to North America, was first recorded in Europe in 2003, in Budapest, and then began to spread quickly. In 2019–2021, we first detected P. fraxinifolii in Belarus (Brest) and eight regions of European Russia, namely Astrakhan, Nizhny Novgorod, Samara, Saratov, Smolensk, Tambov, Volgograd and Voronezh regions. By 2021, P. fraxinifolii has spread over a vast territory in Europe: from Spain in the west to the Volga River in the east. The distance between the westernmost and easternmost localities is 4180 km. The known range is disjunctive: Armenia, Belarus, Bulgaria, Germany, Great Britain, Hungary, Poland, Romania, Spain and 16 regions of European Russia. This case indicates that some alien pests are able to occupy the whole of Europe in less than two decades after the first record in the continent. It is known that P. fraxinifolii can infest native ash species F. excelsior, but all our findings, as well as most findings indicated in the literature, were on F. pennsylvanica introduced from North America. We never found P. fraxinifolii on F. excelsior even near infested F. pennsylvanica trees